Reflection of floor materials
You need a Glossy shader for this.


Open a node editor.
Go to the material tab (in the first set, looks like a ball), and then make sure you're in the object tab (in the second set, looks like a cube).
Select (right-click) the Diffuse BSDF node.
Press Shift+S and switch its type to a Glossy BSDF.


This will give you reflections. You can play with the reflection color and roughness until it looks right.

See the manual for more information on Cycles materials.